1. Field of the Invention
The invention relates generally to a method of permanent hair removal using laser light. More specifically, the invention relates to the transcutaneous use of laser light to target the sebum that coats the hair, heating the sebum which transfers heat first to the hair and hair root and then to the papilla and papillary blood vessels via conduction, thus destroying the hair by photothermolysis while avoiding significant damage to surrounding skin or tissue.
2. Description of the Prior Art
Currently available laser hair removal methods may be classified as either intrafollicular or transcutaneous in nature. Intrafollicular methods comprise the delivery of laser light through a small probe tip which is inserted into the hair follicle. The light utilized is of a wavelength which is readily absorbed by either the melanin in the hair or the hemoglobin in the blood vessels surrounding the papilla. This absorption of light energy produces heat, resulting in damage to the hair shaft, photocoagulation of the tissue surrounding the papilla, and subsequent destruction of the hair. This process is a painstaking, time-consuming process which must be administered by a skilled operator. When targeting melanin, this method losses effectiveness when used on lighter haired patients.
Some transcutaneous laser hair removal methods currently available utilize a substance which is massaged into the skin to penetrate the hair ducts. After cleaning the substance from the skin's surface, light of a wavelength which passes through the skin, but which is absorbed by the substance, is directed onto the treated area. The absorption of energy by the substance applied to the hair duct causes photocoagulation of the tissue surrounding the papilla and results in destruction of the hair. Although this method allows for treatment of a sizable area of skin, it requires the inconvenient, time consuming application of the light-absorbing substance. In addition, great care must be taken to completely remove the substance from the skin's surface prior to the laser treatment to avoid damage to the skin.
Other transcutaneous laser hair removal methods involve the delivery of light which is absorbed to one extent or another by the melanin in the base of the follicle. Wavelengths utilized range from the deep red to the very near IR (&lt;900 nm). This light is only weakly absorbed by blood and blood components, enabling it to pass relatively unabsorbed through light-colored skin. Dark-skinned individuals and persons with lighter-colored hair are not good candidates for hair removal in this approach.
Because of the disadvantages associated with both methods of hair removal in use today, a new method is needed which provides faster, more convenient, and less painful permanent hair removal without damage to the patient's skin.